"Today, we're starting a new experiment: Google Shopping Express," Google Shopping Express product management director Tom Fallows wrote on the company's website. "It's a local delivery service that we hope will make it possible for you to get the items you order online the same day, and at a low cost."

Fallows wrote that it was still "incredibly early," and the service would only be available to a small number of people in the Bay Area. But the company is inviting people in San Francisco, San Jose and San Mateo to sign up to test the new program. Early testers are getting six months' free, unlimited, same-day delivery.

"The pilot will expand as we work out the kinks, so please stay tuned," Fallows wrote.

Drug Store News, citing published reports, reported last week that Google was planning to launch the service, apparently as a competitor to Amazon Prime, but that it was trying to keep the service quiet by instructing employees not to talk to the press about it and avoid shipping products to their homes if they had spouses or roommates who worked with the media.